﻿/* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=2 autoindent cindent expandtab: */
/* Copyright 2012 Mozilla Foundation
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
/* globals VBArray */

'use strict';

// Checking if the typed arrays are supported
(function checkTypedArrayCompatibility()
{
	if (typeof Uint8Array !== 'undefined')
	{
		// some mobile versions do not support subarray (e.g. safari 5 / iOS)
		if (typeof Uint8Array.prototype.subarray === 'undefined')
		{
			Uint8Array.prototype.subarray = function subarray(start, end)
			{
				return new Uint8Array(this.slice(start, end));
			};
			Float32Array.prototype.subarray = function subarray(start, end)
			{
				return new Float32Array(this.slice(start, end));
			};
		}

		// some mobile version might not support Float64Array
		if (typeof Float64Array === 'undefined')
			window.Float64Array = Float32Array;

		return;
	}

	function subarray(start, end)
	{
		return new TypedArray(this.slice(start, end));
	}

	function setArrayOffset(array, offset)
	{
		if (arguments.length < 2)
			offset = 0;
		for (var i = 0, n = array.length; i < n; ++i, ++offset)
			this[offset] = array[i] & 0xFF;
	}

	function TypedArray(arg1)
	{
		var result;
		if (typeof arg1 === 'number')
		{
			result = [];
			for (var i = 0; i < arg1; ++i)
				result[i] = 0;
		} else if ('slice' in arg1)
		{
			result = arg1.slice(0);
		} else
		{
			result = [];
			for (var i = 0, n = arg1.length; i < n; ++i)
			{
				result[i] = arg1[i];
			}
		}

		result.subarray = subarray;
		result.buffer = result;
		result.byteLength = result.length;
		result.set = setArrayOffset;

		if (typeof arg1 === 'object' && arg1.buffer)
			result.buffer = arg1.buffer;

		return result;
	}

	window.Uint8Array = TypedArray;

	// we don't need support for set, byteLength for 32-bit array
	// so we can use the TypedArray as well
	window.Uint32Array = TypedArray;
	window.Int32Array = TypedArray;
	window.Uint16Array = TypedArray;
	window.Float32Array = TypedArray;
	window.Float64Array = TypedArray;
})();

// Object.create() ?
(function checkObjectCreateCompatibility()
{
	if (typeof Object.create !== 'undefined')
		return;

	Object.create = function objectCreate(proto)
	{
		function Constructor() { }
		Constructor.prototype = proto;
		return new Constructor();
	};
})();

// Object.defineProperty() ?
(function checkObjectDefinePropertyCompatibility()
{
	if (typeof Object.defineProperty !== 'undefined')
	{
		var definePropertyPossible = true;
		try
		{
			// some browsers (e.g. safari) cannot use defineProperty() on DOM objects
			// and thus the native version is not sufficient
			Object.defineProperty(new Image(), 'id', { value: 'test' });
			// ... another test for android gb browser for non-DOM objects
			var Test = function Test() { };
			Test.prototype = { get id() { } };
			Object.defineProperty(new Test(), 'id',
			  { value: '', configurable: true, enumerable: true, writable: false });
		} catch (e)
		{
			definePropertyPossible = false;
		}
		if (definePropertyPossible) return;
	}

	Object.defineProperty = function objectDefineProperty(obj, name, def)
	{
		delete obj[name];
		if ('get' in def)
			obj.__defineGetter__(name, def['get']);
		if ('set' in def)
			obj.__defineSetter__(name, def['set']);
		if ('value' in def)
		{
			obj.__defineSetter__(name, function objectDefinePropertySetter(value)
			{
				this.__defineGetter__(name, function objectDefinePropertyGetter()
				{
					return value;
				});
				return value;
			});
			obj[name] = def.value;
		}
	};
})();

// Object.keys() ?
(function checkObjectKeysCompatibility()
{
	if (typeof Object.keys !== 'undefined')
		return;

	Object.keys = function objectKeys(obj)
	{
		var result = [];
		for (var i in obj)
		{
			if (obj.hasOwnProperty(i))
				result.push(i);
		}
		return result;
	};
})();

// No readAsArrayBuffer ?
(function checkFileReaderReadAsArrayBuffer()
{
	if (typeof FileReader === 'undefined')
		return; // FileReader is not implemented
	var frPrototype = FileReader.prototype;
	// Older versions of Firefox might not have readAsArrayBuffer
	if ('readAsArrayBuffer' in frPrototype)
		return; // readAsArrayBuffer is implemented
	Object.defineProperty(frPrototype, 'readAsArrayBuffer', {
		value: function fileReaderReadAsArrayBuffer(blob)
		{
			var fileReader = new FileReader();
			var originalReader = this;
			fileReader.onload = function fileReaderOnload(evt)
			{
				var data = evt.target.result;
				var buffer = new ArrayBuffer(data.length);
				var uint8Array = new Uint8Array(buffer);

				for (var i = 0, ii = data.length; i < ii; i++)
					uint8Array[i] = data.charCodeAt(i);

				Object.defineProperty(originalReader, 'result', {
					value: buffer,
					enumerable: true,
					writable: false,
					configurable: true
				});

				var event = document.createEvent('HTMLEvents');
				event.initEvent('load', false, false);
				originalReader.dispatchEvent(event);
			};
			fileReader.readAsBinaryString(blob);
		}
	});
})();

// No XMLHttpRequest.response ?
(function checkXMLHttpRequestResponseCompatibility()
{
	var xhrPrototype = XMLHttpRequest.prototype;
	if (!('overrideMimeType' in xhrPrototype))
	{
		// IE10 might have response, but not overrideMimeType
		Object.defineProperty(xhrPrototype, 'overrideMimeType', {
			value: function xmlHttpRequestOverrideMimeType(mimeType) { }
		});
	}
	if ('response' in xhrPrototype ||
		'mozResponseArrayBuffer' in xhrPrototype ||
		'mozResponse' in xhrPrototype ||
		'responseArrayBuffer' in xhrPrototype)
		return;
	// IE9 ?
	if (typeof VBArray !== 'undefined')
	{
		Object.defineProperty(xhrPrototype, 'response', {
			get: function xmlHttpRequestResponseGet()
			{
				return new Uint8Array(new VBArray(this.responseBody).toArray());
			}
		});
		return;
	}

	// other browsers
	function responseTypeSetter()
	{
		// will be only called to set "arraybuffer"
		this.overrideMimeType('text/plain; charset=x-user-defined');
	}
	if (typeof xhrPrototype.overrideMimeType === 'function')
	{
		Object.defineProperty(xhrPrototype, 'responseType',
							  { set: responseTypeSetter });
	}
	function responseGetter()
	{
		var text = this.responseText;
		var i, n = text.length;
		var result = new Uint8Array(n);
		for (i = 0; i < n; ++i)
			result[i] = text.charCodeAt(i) & 0xFF;
		return result;
	}
	Object.defineProperty(xhrPrototype, 'response', { get: responseGetter });
})();

// window.btoa (base64 encode function) ?
(function checkWindowBtoaCompatibility()
{
	if ('btoa' in window)
		return;

	var digits =
	  'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=';

	window.btoa = function windowBtoa(chars)
	{
		var buffer = '';
		var i, n;
		for (i = 0, n = chars.length; i < n; i += 3)
		{
			var b1 = chars.charCodeAt(i) & 0xFF;
			var b2 = chars.charCodeAt(i + 1) & 0xFF;
			var b3 = chars.charCodeAt(i + 2) & 0xFF;
			var d1 = b1 >> 2, d2 = ((b1 & 3) << 4) | (b2 >> 4);
			var d3 = i + 1 < n ? ((b2 & 0xF) << 2) | (b3 >> 6) : 64;
			var d4 = i + 2 < n ? (b3 & 0x3F) : 64;
			buffer += (digits.charAt(d1) + digits.charAt(d2) +
					   digits.charAt(d3) + digits.charAt(d4));
		}
		return buffer;
	};
})();

// Function.prototype.bind ?
(function checkFunctionPrototypeBindCompatibility()
{
	if (typeof Function.prototype.bind !== 'undefined')
		return;

	Function.prototype.bind = function functionPrototypeBind(obj)
	{
		var fn = this, headArgs = Array.prototype.slice.call(arguments, 1);
		var bound = function functionPrototypeBindBound()
		{
			var args = Array.prototype.concat.apply(headArgs, arguments);
			return fn.apply(obj, args);
		};
		return bound;
	};
})();

// IE9/10 text/html data URI
(function checkDataURICompatibility()
{
	if (!('documentMode' in document) ||
		document.documentMode !== 9 && document.documentMode !== 10)
		return;
	// overriding the src property
	var originalSrcDescriptor = Object.getOwnPropertyDescriptor(
	  HTMLIFrameElement.prototype, 'src');
	Object.defineProperty(HTMLIFrameElement.prototype, 'src', {
		get: function htmlIFrameElementPrototypeSrcGet() { return this.$src; },
		set: function htmlIFrameElementPrototypeSrcSet(src)
		{
			this.$src = src;
			if (src.substr(0, 14) != 'data:text/html')
			{
				originalSrcDescriptor.set.call(this, src);
				return;
			}
			// for text/html, using blank document and then
			// document's open, write, and close operations
			originalSrcDescriptor.set.call(this, 'about:blank');
			setTimeout((function htmlIFrameElementPrototypeSrcOpenWriteClose()
			{
				var doc = this.contentDocument;
				doc.open('text/html');
				doc.write(src.substr(src.indexOf(',') + 1));
				doc.close();
			}).bind(this), 0);
		},
		enumerable: true
	});
})();

// HTMLElement dataset property
(function checkDatasetProperty()
{
	var div = document.createElement('div');
	if ('dataset' in div)
		return; // dataset property exists

	Object.defineProperty(HTMLElement.prototype, 'dataset', {
		get: function()
		{
			if (this._dataset)
				return this._dataset;

			var dataset = {};
			for (var j = 0, jj = this.attributes.length; j < jj; j++)
			{
				var attribute = this.attributes[j];
				if (attribute.name.substring(0, 5) != 'data-')
					continue;
				var key = attribute.name.substring(5).replace(/\-([a-z])/g,
				  function(all, ch) { return ch.toUpperCase(); });
				dataset[key] = attribute.value;
			}

			Object.defineProperty(this, '_dataset', {
				value: dataset,
				writable: false,
				enumerable: false
			});
			return dataset;
		},
		enumerable: true
	});
})();

// HTMLElement classList property
(function checkClassListProperty()
{
	var div = document.createElement('div');
	if ('classList' in div)
		return; // classList property exists

	function changeList(element, itemName, add, remove)
	{
		var s = element.className || '';
		var list = s.split(/\s+/g);
		if (list[0] === '') list.shift();
		var index = list.indexOf(itemName);
		if (index < 0 && add)
			list.push(itemName);
		if (index >= 0 && remove)
			list.splice(index, 1);
		element.className = list.join(' ');
	}

	var classListPrototype = {
		add: function(name)
		{
			changeList(this.element, name, true, false);
		},
		remove: function(name)
		{
			changeList(this.element, name, false, true);
		},
		toggle: function(name)
		{
			changeList(this.element, name, true, true);
		}
	};

	Object.defineProperty(HTMLElement.prototype, 'classList', {
		get: function()
		{
			if (this._classList)
				return this._classList;

			var classList = Object.create(classListPrototype, {
				element: {
					value: this,
					writable: false,
					enumerable: true
				}
			});
			Object.defineProperty(this, '_classList', {
				value: classList,
				writable: false,
				enumerable: false
			});
			return classList;
		},
		enumerable: true
	});
})();

// Check console compatability
(function checkConsoleCompatibility()
{
	if (!('console' in window))
	{
		window.console = {
			log: function() { },
			error: function() { },
			warn: function() { }
		};
	} else if (!('bind' in console.log))
	{
		// native functions in IE9 might not have bind
		console.log = (function(fn)
		{
			return function(msg) { return fn(msg); };
		})(console.log);
		console.error = (function(fn)
		{
			return function(msg) { return fn(msg); };
		})(console.error);
		console.warn = (function(fn)
		{
			return function(msg) { return fn(msg); };
		})(console.warn);
	}
})();

// Check onclick compatibility in Opera
(function checkOnClickCompatibility()
{
	// workaround for reported Opera bug DSK-354448:
	// onclick fires on disabled buttons with opaque content
	function ignoreIfTargetDisabled(event)
	{
		if (isDisabled(event.target))
		{
			event.stopPropagation();
		}
	}
	function isDisabled(node)
	{
		return node.disabled || (node.parentNode && isDisabled(node.parentNode));
	}
	if (navigator.userAgent.indexOf('Opera') != -1)
	{
		// use browser detection since we cannot feature-check this bug
		document.addEventListener('click', ignoreIfTargetDisabled, true);
	}
})();

// Checks if navigator.language is supported
(function checkNavigatorLanguage()
{
	if ('language' in navigator)
		return;
	Object.defineProperty(navigator, 'language', {
		get: function navigatorLanguage()
		{
			var language = navigator.userLanguage || 'en-US';
			return language.substring(0, 2).toLowerCase() +
			  language.substring(2).toUpperCase();
		},
		enumerable: true
	});
})();
